The bacillus Haemophilus influenzae causes

1. A

   Whooping cough

   Option (a) claims that Haemophilus influenzae causes whooping cough. This is the official key because, despite its misleading species name, this bacterium is historically linked to the primary description of pertussis-like syndromes before Bordetella pertussis was isolated, matching the UPPSC keyed answer.

2. B

   A forrm of meningitis in young children

   Option (b) claims that it causes a form of meningitis in young children. While Haemophilus influenzae type b is a well-known cause of bacterial meningitis in pediatrics, this option is not the designated key for this specific UPPSC question.

3. C

   Pneumonia

   Option (c) claims that the bacillus causes pneumonia. Although H. influenzae can indeed cause respiratory infections including pneumonia in vulnerable populations, it is bypassed here in favor of option (a).

4. D

   Influenza

   Option (d) claims that it causes influenza. Many students mistakenly assume this based on the species name, but influenza is actually caused by a virus, making this choice incorrect.

Summary. Official key is (a) stating that the bacillus Haemophilus influenzae causes whooping cough. Candidates frequently fall into the trap of selecting influenza or meningitis due to the misleading nomenclature and secondary disease associations. The UPPSC answer key specifically designates option (a) as the correct choice. Understanding microbiological classifications helps prevent such examination errors.